Advice on starting issue '99 C2500 Suburban

[DaveNay]

Help....seeking advice on where to go next troubleshooting starting issues on my '99 Suburban C2500 with 7.4L

This fall the truck developed an issue where there wasn't enough power to turn over the starter. When it first started having troubles, I could tighten the positive battery cable and it would start right up. It gradually deteriorated to the point where this trick didn't work. Looking at the battery cable ends, it was clear there was a lot of corrosion on and in them. I then replaced both positive battery cables and bought a new battery at the same time. This seemed to do the trick and the truck started perfectly on the first turn of the key for a month.

Until this morning.

Now the same issue is back where the truck won't start. All of the interior and exterior lights work, and when I turn the key I can hear the starter solenoid engage, but the starter doesn't turn.

I have checked and tightened the battery cables again (they were about 1/8th turn loose, should still have been making adequate connection). I have not had a chance to crawl underneath and check the positive cable to the starter to make sure it is still tight.

Any other thoughts? Is the starter itself going bad? Alternator not maintaining charge (I don't think so....when diagnosing this the first time around, the battery was receiving 14.8v across the terminals with the engine running).

 

[justcuz]

Check your starter terminal again and replace the lock washer, if it has one, with a star washer. That should keep it tight. If that dates not work then have the starter tested. If the starter is bad, replace it with a dense gear reduction starter. They are pricey, but you will never buy another starter.

 

[DaveNay]

I checked the cable connection to the starter, and it is still nice and tight. I tried thumping the starter solenoid with the end of the ratchet, but no luck (I know, percussive repairs don't usually work.....)

Then I put my big battery charger (250A) on the battery, and it started right up....so two possibilities. 1) The starter is indeed going bad and the extra juice of the charger was enough to overcome internal resistance; or 2) the alternator is going bad and isn't able to maintain the battery over a period of weeks, and the charger was working as a regular old jump start.

I have left the charger on the truck for now at 60A, so I should be able to pull it off and try to start it normally in a few hours.

 

[justcuz]

Alternator is easy to test, check battery voltage before starting engine. Start it up, if voltage is up to 13.75 to 14.25 alternator is functional. If you don't have a volt meter, a small screwdriver will magnetize itself to the back bearing cover of the alternator if it's working.
You may have bad bearings in the starter. If they are real bad the armature will ground against the internals instead of spinning. The starter I referred to earlier is a Denso gear reduction starter.
Pep Boys used to sell a rebuilding kit for a starter, but I have not seen one in a while.
I would have your battery and starter tested.

 

[DaveNay]

Alternator is easy to test, check battery voltage before starting engine. Start it up, if voltage is up to 13.75 to 14.25 alternator is functional. If you don't have a volt meter, a small screwdriver will magnetize itself to the back bearing cover of the alternator if it's working.
You may have bad bearings in the starter. If they are real bad the armature will ground against the internals instead of spinning. The starter I referred to earlier is a Denso gear reduction starter.
Pep Boys used to sell a rebuilding kit for a starter, but I have not seen one in a while.
I would have your battery and starter tested.

As I mentioned earlier....voltage across the battery is around 14.8v measured with a multimeter. The battery is only a month old, I replaced it at the same time as the positive battery cables.

 

[1stDeuce]

I think your truck may have multiple problems, and you've only fixed a few of them... First, in IL, I'm sure the cables were DONE, and that would cause the issues you report initially. You replaced them and took care of that issue.

It sounds like you now have a starter solenoid that isn't always making contact inside. The solenoid basically is a powered magnet that causes a washer to move up against the back side of the lug the battery cable is attached to, and the back side of the one directly below, which goes to the starter windings. That completes the circuit to both engage the starter and power it to spin the motor. Over time, the arcing wears out that washer and you get a "click" when the solenoid engages, but the bad contact doesn't complete the circuit to power the starter motor. If you try again, sometimes several times, it'll finally crank over. Time for a new starter, or a rebuild on your current one if there's a shop close by that does that sort of thing. (Not many left...)

If it wasn't cranking AT ALL before you put the charger on it, but the battery voltage read 12-ish, then you don't have a battery problem, you have a starter problem. A battery problem would slowly crank, then nothing, and the lights would go out and it would make the dead battery clicking sound while all the relays in the truck power up and down... You didn't have that, so most likely it's the solenoid, and you just got lucky and it made contact, or your charger raising the voltage significantly burned through the crud and made contact.

If EVERYTHING drops dead the second the starter solenoid goes "click", then you still have a bad connection somewhere. Check the ground cables, and re-check the power cables. (I don't think that's your problem.)

 

[82fb]

Sounds like your negative cable was not changed? Get it changed.
How does the new positive battery cable just magically come loose? My guess is it was never tightened adequately, then developed corrosion and needs to be cleaned and re-installed.

 

[DaveNay]

It sounds like you now have a starter solenoid that isn't always making contact inside. The solenoid basically is a powered magnet that causes a washer to move up against the back side of the lug the battery cable is attached to, and the back side of the one directly below, which goes to the starter windings. That completes the circuit to both engage the starter and power it to spin the motor. Over time, the arcing wears out that washer and you get a "click" when the solenoid engages, but the bad contact doesn't complete the circuit to power the starter motor. If you try again, sometimes several times, it'll finally crank over. Time for a new starter, or a rebuild on your current one if there's a shop close by that does that sort of thing. (Not many left...)

I am leaning more toward the starter being the issue myself at this time. Believe it or not, I do have a reputable starter & alternator rebuild shop right down the road from me. I have used their services in the past.

Here's the latest info: On Thursday, I left the battery charger on the truck at 60A for about 3 hours, then at 2A for about 8 hours. The next morning the truck started right up without the charger boost. It has also started up a dozen times since then without and problems. When it starts, there is no hesitation from the starter motor and it cranks with full power. When it doesn't start, it just has the single click with no cranking, but the truck does not "go dead"; there are still lights working, just no crank.

Is it possible that it is not getting enough time to recharge the battery after starting? My wife usually drives the truck since she only has a 7 mile commute and I have a 40 mile commute. On Friday, I took the truck to work, so it had 45 minutes to recharge the battery instead of 10-15 minutes when she drives. Could the battery possible be being depleted after many days of a short recharge cycle?

Sounds like your negative cable was not changed? Get it changed.
How does the new positive battery cable just magically come loose? My guess is it was never tightened adequately, then developed corrosion and needs to be cleaned and re-installed.

Correct. The negative cable was not replaced since it did not appear to be in bad condition at all. That is a good cheap option to investigate though. The positive battery cable did not "magically" come loose. I was able to tighten it very slightly more when I checked. I am being careful to not over tighten because the side post batteries that GM uses are known to strip out the threads inside the battery contact.

 

[justcuz]

Check the ground cable with an ohm meter. Remove it from the car and wiggle it with the meter connected to the ends to see if you have internal breakdown of the cable. Clean the ground cable attachment to the engine or chassis (wherever it is hooked up.)
If you think your wife's driving cycle is not charging the battery enough, check the battery voltage after a couple days. If you checked alternator output with the engine running and you have 14.8 volts, then I think you answered your own question there.
The only way you can have short cycle failure of the battery charge is if the regulator is shutting down the alternator charge time or your battery is faulty. If you can swap batteries between vehicles and see if the problem transfers to the other vehicle. If it does it is the battery, if not it is the alternator.
Also like 1stduece said check the solenoid. Starters are easy to test, disassemble and repair. The washer he is referring to is easy to turn around and use the other side to make a good connection. I've seen old ones almost burned completely through from electrical arcing.

 

[1stDeuce]

Generally speaking, ground cables don't corrode like the positive cables do. It's an electrical thing... Feel free to check them, but I'm sure they are fine. I've never seen corroded ground cables... The positive cable acts like the sacrificial anode because of the voltage potential, and the ground cable stays in really good condition.

If it's not cranking really slow, or doing the dead battery clicks when you engage the starter, it's not a cable problem anymore. I don't think you have a charging problem either. That would give the same clicking relay sounds that really rotten battery cables might produce. If your battery was getting too low to actually spin the motor, you'd get a single click, followed by all the lights dimming to nothing and a lot of clicking of other relays due to low voltage.

A single click while everything else stays on is the starter solenoid. Get it rebuilt and move on. (Hopefully it isn't a total disaster to take out...)

 

[DaveNay]

Generally speaking, ground cables don't corrode like the positive cables do. It's an electrical thing... Feel free to check them, but I'm sure they are fine. I've never seen corroded ground cables... The positive cable acts like the sacrificial anode because of the voltage potential, and the ground cable stays in really good condition.

If it's not cranking really slow, or doing the dead battery clicks when you engage the starter, it's not a cable problem anymore. I don't think you have a charging problem either. That would give the same clicking relay sounds that really rotten battery cables might produce. If your battery was getting too low to actually spin the motor, you'd get a single click, followed by all the lights dimming to nothing and a lot of clicking of other relays due to low voltage.

A single click while everything else stays on is the starter solenoid. Get it rebuilt and move on. (Hopefully it isn't a total disaster to take out...)

I have never seen a corroded negative cable either...that's why I didn't replace it along with the positive cables.

Rebuilding the starter is the plan. It doesn't look too difficult to pull, especially since it is only two wheel drive.

 

[82fb]

Please report back when you get this thing running again. Always good to hear the fix. Having a hard time thinking its the starter based on your narrative of no start, change positive cables, starts fine for a month, then no start, clean cables, and it starts again. Seems like getting adequate juice to the starter is your problem.

 

[justcuz]

If you rebuild the starter yourself, maybe put up some pictures of the disassembled solenoid so folks can see that contact washer.
I lube the bearings with a mixture of red grease on a q tip with a couple drops of Marvel Mystery oil.

 

[rayra]

It seems you are not getting a good circuit, despite your battery having the power.

Engine ground cable, back of the block.
Battery negative connection to frame.
Starter Solenoid, almost certainly from what you described as max volts / amps doing the trick.

And the simplest test of alternator output is start the vehicle and disconnect the battery while the vehicle is running.

 

[justcuz]

Davenay, when you disassemble the solenoid, you will remove the front Bakelite cover to reveal the big washer. When the solenoid is energized the washer makes contact with the big battery connection to continue the circuit to the starter motor. The surface of the washer and back side of the large stud are what erode over time. The next thing that will cause the starter not to spin is bad armature bushings that allow the armature to ground against the magnets instead of spinning.
Like I said earlier, if you don't want to mess with any of that, buy a Denso gear reduction starter and never worry about it again.